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Where does the air on the space station come from? Publications by employees of JSC NIIkhimmash

We are not astronauts, we are not pilots,
Not engineers, not doctors.
And we are plumbers:
We drive water out of urine!
And not fakirs, brothers, like us,
But without boasting, we say:
The water cycle in nature we
We will repeat it in our system!
Our science is very precise.
Just let your thoughts go.
We will distill wastewater
For casseroles and compote!
Having passed all the Milky roads,
You won't lose weight at the same time
With complete self-sufficiency
Our space systems.
After all, even the cakes are excellent,
Lula kebab and kalachi
Ultimately - from the original
Material and urine!
Do not refuse, if possible,
When we ask in the morning
Fill the flask with a total of
At least a hundred grams each!
We must confess in a friendly manner,
What are the benefits of being friends with us:
After all, without recycling
You can't live in this world!!!

(Author - Valentin Filippovich Varlamov - pseudonym V. Vologdin)

Water is the basis of life. On our planet for sure. On some Gamma Centauri, everything may be different. With the advent of space exploration, the importance of water for humans has only increased. A lot depends on H2O in space, from the operation of the space station itself to the production of oxygen. The first spacecraft did not have a closed “water supply” system. All water and other “consumables” were taken on board initially, from Earth.

“Previous space missions - Mercury, Gemini, Apollo, took with them all the necessary supplies of water and oxygen and dumped liquid and gaseous waste into space", explains Robert Bagdigian of the Marshall Center.

To put it briefly: the life support systems of cosmonauts and astronauts were “open” - they relied on support from their home planet.

I’ll talk about iodine and the Apollo spacecraft, the role of toilets and options (UdSSR or USA) for waste disposal on early spacecraft another time.

In the photo: portable life support system for the Apollo 15 crew, 1968.

Leaving the reptilian, I swam to the cabinet of sanitary products. Turning his back to the meter, he took out a soft corrugated hose and unbuttoned his trousers.
– Need for waste disposal?
God…
Of course, I didn’t answer. He turned on the suction and tried to forget about the curious gaze of the reptilian boring into his back. I hate these small everyday problems.

“Stars are cold toys”, S. Lukyanenko

I'll go back to water and O2.

Today there is a partially closed water regeneration system on the ISS, and I will try to tell you about the details (to the extent that I have understood this myself).

Retreat:
On February 20, 1986, the Soviet orbital station Mir entered orbit.

To deliver 30,000 liters of water on board the MIR orbital station and the ISS, it would be necessary to organize an additional 12 launches of the Progress transport ship, the payload of which is 2.5 tons. If we take into account the fact that the Progress ships are equipped with drinking water tanks of the Rodnik type with a capacity of 420 liters, then the number of additional launches of the Progress transport ship should have increased several times.

On the ISS, zeolite absorbers of the Air system capture carbon dioxide (CO2) and release it into the outboard space. The oxygen lost in CO2 is replenished through the electrolysis of water (its decomposition into hydrogen and oxygen). This is done on the ISS by the Electron system, which consumes 1 kg of water per person per day. Hydrogen is currently being vented overboard, but in the future it will help convert CO2 into valuable water and emitted methane (CH4). And of course, just in case there are oxygen bombs and cylinders on board.

In the photo: an oxygen generator and a running machine on the ISS, which failed in 2011.

In the photo: astronauts are setting up a system for degassing liquids for biological experiments in microgravity conditions in the Destiny laboratory.

In the photo: Sergey Krikalev with the Electron water electrolysis device

Unfortunately, the complete circulation of substances at orbital stations has not yet been achieved. At this level of technology, it is not possible to synthesize proteins, fats, carbohydrates and other biologically active substances using physicochemical methods. Therefore, carbon dioxide, hydrogen, moisture-containing and dense waste from the life of astronauts are removed into the vacuum of outer space.

This is what a space station bathroom looks like

The ISS service module has introduced and operates the Vozdukh and BMP purification systems, the SRV-K2M improved water regeneration system from condensate and the Elektron-VM oxygen generation system, as well as the SPK-UM urine collection and preservation system. The productivity of the improved systems has been increased by more than 2 times (ensures the vital functions of a crew of up to 6 people), and energy and mass costs have been reduced.

Over a five year period (data for 2006) During their operation, 6.8 tons of water and 2.8 tons of oxygen were regenerated, which made it possible to reduce the weight of cargo delivered to the station by more than 11 tons.

The delay in including the SRV-UM system for regenerating water from urine into the LSS complex did not allow for the regeneration of 7 tons of water and reducing the delivery weight.

"Second Front" - Americans

Process water from the American ECLSS apparatus is supplied to the Russian system and the American OGS (Oxygen Generation System), where it is then “processed” into oxygen.

The process of recovering water from urine is a complex technical task: “Urine is much “dirtier” than water vapor, explains Carrasquillo, “It can corrode metal parts and clog pipes.” The ECLSS system uses a process called vapor compression distillation to purify urine: the urine is boiled until the water in it turns into steam. The steam—naturally purified water in a vapor state (minus traces of ammonia and other gases)—rises into the distillation chamber, leaving a concentrated brown slurry of impurities and salts that Carrasquillo charitably calls “brine” (which is then released into outer space). The steam then cools and the water condenses. The resulting distillate is mixed with moisture condensed from the air and filtered to a state suitable for drinking. The ECLSS system is capable of recovering 100% moisture from air and 85% water from urine, which corresponds to a total efficiency of about 93%.

The above, however, applies to the operation of the system in terrestrial conditions. In space, an additional complication arises - the steam does not rise up: it is not able to rise into the distillation chamber. Therefore, in the ECLSS model for the ISS “...we rotate the distillation system to create artificial gravity to separate the vapors and brine.”, explains Carrasquillo.

Prospects:
There are known attempts to obtain synthetic carbohydrates from the waste products of astronauts for the conditions of space expeditions according to the following scheme:

According to this scheme, waste products are burned to form carbon dioxide, from which methane is formed as a result of hydrogenation (Sabatier reaction). Methane can be transformed into formaldehyde, from which monosaccharide carbohydrates are formed as a result of a polycondensation reaction (Butlerov reaction).

However, the resulting carbohydrate monosaccharides were a mixture of racemates - tetroses, pentoses, hexoses, heptoses, which did not have optical activity.

Note I'm even afraid to delve into the "wiki knowledge" to understand its meaning.

Modern life-support systems, after their appropriate modernization, can be used as the basis for the creation of life-support systems necessary for the exploration of deep space.

The LSS complex will ensure almost complete reproduction of water and oxygen at the station and can be the basis of LSS complexes for planned flights to Mars and the organization of a base on the Moon.

Much attention is paid to creating systems that ensure the most complete circulation of substances. For this purpose, they will most likely use the process of hydrogenation of carbon dioxide according to the Sabatier or Bosch-Boudoir reaction, which will allow for the circulation of oxygen and water:

CO2 + 4H2 = CH4 + 2H2O
CO2 + 2H2 = C + 2H2O

In the case of an exobiological ban on the release of CH4 into the vacuum of outer space, methane can be transformed into formaldehyde and non-volatile carbohydrate monosaccharides by the following reactions:

CH4 + O2 = CH2O + H2O
polycondensation
nСН2О - ? (CH2O)n
Ca(OH)2

I would like to note that the sources of environmental pollution at orbital stations and during long interplanetary flights are:

- interior construction materials (polymer synthetic materials, varnishes, paints)
- humans (during perspiration, transpiration, with intestinal gases, during sanitary and hygienic measures, medical examinations, etc.)
- working electronic equipment
- links of life support systems (sewage system - automated control system, kitchen, sauna, shower)
and much more

Obviously, it will be necessary to create an automatic system for operational monitoring and management of the quality of the living environment. A certain ASOKUKSO?

My youngest son started putting together a “research gang” at school today to grow Chinese lettuce in an old microwave. They probably decided to provide themselves with greens when traveling to Mars. You will have to buy an old microwave at AVITO, because... Mine are still working. Don't break it on purpose, right?

Note in the photo, of course, is not my child, and not the future victim of the microwave experiment.

As I promised marks@marks, if something comes up, I’ll post photos and the result to GIC. I can send the grown salad by Russian Post to those who wish, for a fee, of course. Add tags

In the unusual conditions of an extra-atmospheric flight, cosmonauts must be provided with all conditions for work and rest. They need to eat, drink, breathe, rest, and sleep for the appropriate amount of time. Such simple and ordinary questions for earthly existence in space conditions develop into complex scientific and technical problems.

A person can go without food for quite a long time, without water - for several days. But without air he can only live for a few minutes. Breathing is the most important function of the human body. How is it ensured in space flight?

The free volume in spacecraft is small. typically has about 9 cubic meters of air on board. And behind the walls of the ship there is almost complete vacuum, the remnants of an atmosphere whose density is millions of times less than that of the Earth’s surface.

9 cubic meters is all that astronauts have to breathe. But this is a lot. The only question is what this volume will be filled with, what the astronauts will breathe.

The atmosphere surrounding a person on Earth, in a dry state, contains by weight 78.09 percent nitrogen, 20.95 percent oxygen, 0.93 percent argon, 0.03 percent carbon dioxide. The amount of other gases in it is practically insignificant.

Humans and almost all living things on Earth are accustomed to breathing this gas mixture. But the capabilities of the human body are wider. Of the total atmospheric pressure at sea level, oxygen accounts for approximately 160 millimeters. A person can breathe when the oxygen pressure drops to 98 millimeters of mercury, and only below that does “oxygen starvation” occur. But another option is also possible: when the oxygen content in the air is higher than normal. The upper limit of the partial pressure of oxygen possible for humans is 425 millimeters of mercury. At higher concentrations of oxygen, oxygen poisoning occurs. So, the capabilities of the human body allow fluctuations in oxygen content by approximately 4 times. Within even wider limits, our body can tolerate fluctuations in atmospheric pressure: from 160 millimeters of mercury to several atmospheres.

Nitrogen and argon are the inert part of air. Only oxygen takes part in oxidative processes. Therefore, the thought arose: is it possible to replace nitrogen in a spacecraft with a lighter gas, say, helium. A cubic meter of nitrogen weighs 1.25 kilograms, and helium weighs only 0.18 kilograms, that is, seven times less. For spaceships, where every extra kilogram of weight is accounted for, this is by no means indifferent. Experiments have shown that in an oxygen-helium atmosphere a person can breathe normally. This was tested by American aquanauts during long underwater dives.

From a technical point of view, the single-gas atmosphere consisting of pure oxygen also attracts attention. In American spacecraft, astronauts use pure oxygen at a pressure of about 270 millimeters of mercury for breathing. At the same time, equipment for controlling pressure and maintaining the composition of the atmosphere is simpler (and therefore lighter). However, pure oxygen has its drawbacks: there is a risk of fire on the spacecraft; prolonged inhalation of pure oxygen causes unpleasant complications in the respiratory tract.

When creating an artificial environment in domestic spacecraft, the normal earth's atmosphere is taken as a basis. Experts, primarily doctors, insisted that a corner of the home planet be created on board the spaceships with conditions as close as possible to those that surround humans on Earth. All the technical benefits obtained by using a single-gas atmosphere, oxygen-helium and others, were sacrificed for the sake of complete comfort for the astronauts. All parameters are very close to the norms of the atmosphere we breathe on Earth. They show that the automation “holds” the air parameters in the cabin very “tightly” and stably. Astronauts seem to breathe the clean air of the Earth.

After the astronauts board the ship, after its compartments are sealed, the composition of the atmosphere in the ship begins to change. Two astronauts consume about 50 liters of oxygen per hour and emit 80-100 grams of water vapor, carbon dioxide, volatile metabolic products, etc. Then the air conditioning system comes into effect, which brings the atmosphere “to condition”, that is, it maintains all its parameters at optimal level.

Atmospheric regeneration is based on effective, proven physical and chemical processes. There are known chemicals that, when combined with water or carbon dioxide, are capable of releasing oxygen. These are alkali metal superoxides - sodium, potassium, lithium. In order for these reactions to release 50 liters of oxygen - the hourly requirement of two astronauts - 26.4 grams of water are needed. And its release into the atmosphere by two astronauts, as we have already said, reaches 100 grams per hour.

Some of this water is used to produce oxygen, while some is stored in the air to maintain normal relative humidity (within 40-60 percent). Excess water must be captured by special absorbers.

The presence of dust, crumbs, and debris in the air is unacceptable. After all, in zero gravity, all this does not fall to the floor, but floats freely in the atmosphere of the ship and can enter the respiratory tract of the astronauts. There are special filters to clean the air from mechanical contaminants.

So, regeneration of the atmosphere in a ship comes down to the fact that part of the air from the habitable compartments is constantly taken in by a fan and passes through a number of air conditioning system devices. There the air is purified, brought to normal levels in terms of chemical composition, humidity and temperature, and again returned to the astronaut cabin. This air circulation is constant, and its speed and efficiency are constantly controlled by appropriate automation.

For example, if the oxygen content in the ship’s atmosphere has increased excessively, the control system will immediately notice this. She gives the appropriate commands to the executive bodies; The operating mode of the installation is changed to reduce the release of oxygen.

We are not astronauts, we are not pilots,
Not engineers, not doctors.
And we are plumbers:
We drive water out of urine!
And not fakirs, brothers, like us,
But without boasting, we say:
The water cycle in nature we
We will repeat it in our system!
Our science is very precise.
Just let your thoughts go.
We will distill wastewater
For casseroles and compote!
Having passed all the Milky roads,
You won't lose weight at the same time
With complete self-sufficiency
Our space systems.
After all, even the cakes are excellent,
Lula kebab and kalachi
Ultimately - from the original
Material and urine!
Do not refuse, if possible,
When we ask in the morning
Fill the flask with a total of
At least a hundred grams each!
We must confess in a friendly manner,
What are the benefits of being friends with us:
After all, without recycling
You can't live in this world!!!

(Author - Valentin Filippovich Varlamov - pseudonym V. Vologdin)

To put it briefly: the life support systems of cosmonauts and astronauts were “open” - they relied on support from their home planet.

I’ll talk about iodine and the Apollo spacecraft, the role of toilets and options (UdSSR or USA) for waste disposal on early spacecraft another time.

In the photo: portable life support system for the Apollo 15 crew, 1968.

Leaving the reptilian, I swam to the cabinet of sanitary products. Turning his back to the meter, he took out a soft corrugated hose and unbuttoned his trousers.
– Need for waste disposal?
God…
Of course, I didn’t answer. He turned on the suction and tried to forget about the curious gaze of the reptilian boring into his back. I hate these small everyday problems.

“Stars are cold toys”, S. Lukyanenko

I'll go back to water and O2.

Today there is a partially closed water regeneration system on the ISS, and I will try to tell you about the details (to the extent that I have understood this myself).

Retreat:
On February 20, 1986, the Soviet orbital station Mir entered orbit.

In the photo: an oxygen generator and a running machine on the ISS, which failed in 2011.

In the photo: astronauts are setting up a system for degassing liquids for biological experiments in microgravity conditions in the Destiny laboratory.

In the photo: Sergey Krikalev with the Electron water electrolysis device

This is what a space station bathroom looks like

The delay in including the SRV-UM system for regenerating water from urine into the LSS complex did not allow for the regeneration of 7 tons of water and reducing the delivery weight.

"Second Front" - Americans

Process water from the American ECLSS apparatus is supplied to the Russian system and the American OGS (Oxygen Generation System), where it is then “processed” into oxygen.

Prospects:
There are known attempts to obtain synthetic carbohydrates from the waste products of astronauts for the conditions of space expeditions according to the following scheme:

However, the resulting carbohydrate monosaccharides were a mixture of racemates - tetroses, pentoses, hexoses, heptoses, which did not have optical activity.

Note I'm even afraid to delve into the "wiki knowledge" to understand its meaning.

Modern life-support systems, after their appropriate modernization, can be used as the basis for the creation of life-support systems necessary for the exploration of deep space.

CO2 + 4H2 = CH4 + 2H2O
CO2 + 2H2 = C + 2H2O

CH4 + O2 = CH2O + H2O
polycondensation
nСН2О - ? (CH2O)n
Ca(OH)2

I would like to note that the sources of environmental pollution at orbital stations and during long interplanetary flights are:

Obviously, it will be necessary to create an automatic system for operational monitoring and management of the quality of the living environment. A certain ASOKUKSO?

Note in the photo, of course, is not my child, and not the future victim of the microwave experiment.

As I promised marks@marks, if something comes up, I’ll post photos and the result to GIC. I can send the grown lettuce by Russian Post to those who wish, for a fee, of course.

manned flights

Add tags

Water is life. This idea is thousands of years old, but it still has not lost its relevance. With the advent of the space age, the importance of water has only increased, since literally everything in space depends on water, from the operation of the space station itself to the production of oxygen. The first space flights did not have a closed “water supply” system. That is, all the water was taken on board initially, from Earth. Today the ISS has a partially closed water regeneration system, and in this article you will learn more.

Where does water come from on the ISS?

Water regeneration is the re-production of water. From here we need to draw the most important conclusion that water is initially delivered to the ISS from Earth. It is impossible to regenerate water unless it is brought from Earth in the first place. The regeneration process itself reduces spaceflight costs and makes the ISS system less dependent on ground services.

Water delivered from Earth is used repeatedly on the ISS. Currently, several methods of water regeneration are used on the ISS:

Condensation of moisture from the air;
Purification of used water;
Processing of urine and solid waste;

The ISS has special equipment that condenses moisture from the air. Moisture in the air is natural; it exists both in space and on Earth. During their daily life, astronauts can excrete up to 2.5 liters of fluid per day. In addition, the ISS has special filters to purify used water. But considering that how astronauts wash themselves, domestic water consumption differs significantly from that on Earth. The processing of urine and solid waste is a new development, applied on the ISS only since 2010.

At the moment, the ISS requires about 9,000 liters of water per year to operate. This is a total figure that reflects all expenses. Water on the ISS is recycled by approximately 93%, so the volume of water supplied to the ISS is significantly lower. But do not forget that with each complete cycle of water use, its total volume decreases by 7%, which makes the ISS dependent on supplies from Earth.

Since May 29, 2009, the number of crew members has doubled - from 3 to 6 people. At the same time, water consumption has also increased, but modern technologies have made it possible to increase the number of astronauts on the ISS.

Water regeneration in space

When it comes to space, it is important to take into account energy costs, or as they are called in the professional sphere - mass costs, for water production. The first full-fledged water regeneration apparatus appeared at the Mir station, and over the entire period of its existence it made it possible to “save” 58,650 kg of cargo delivered from Earth. Remembering that delivery of 1 kg of cargo costs about 5-6 thousand US dollars, the first full-fledged water reclamation system reduced costs by approximately 300 million US dollars.

Modern Russian water regeneration systems - SRV-K2M and Elektron-VM - make it possible to provide astronauts on the ISS with water by 63%. Biochemical analysis showed that the regenerated water does not lose its original properties and is completely suitable for drinking. Currently, Russian scientists are working on creating a more closed system that will provide 95% of the cosmonauts with water. There are prospects for the development of purification systems that will provide a 100% closed cycle.

The American water regeneration system - ECLSS, was developed in 2008. It allows you not only to collect moisture from the air, but also to regenerate water from urine and solid waste. Despite serious problems and frequent breakdowns during the first two years of operation, today ECLSS can recover 100% of moisture from air and 85% of moisture from urine and solid waste. As a result, a modern apparatus appeared on the ISS that makes it possible to restore up to 93% of the original volume of water.

Water purification

The key to regeneration is water purification. The purification systems collect any water - leftover from cooking, dirty water from washing, and even the sweat of astronauts. All this water is collected in a special distiller, visually similar to a barrel. When purifying water, it is necessary to create artificial gravity; for this, the distiller rotates, while dirty water is driven through filters. The result is pure drinking water, which in its quality even surpasses drinking water in many parts of the Earth.

At the last stage, iodine is added to the water. This chemical helps prevent the proliferation of germs and bacteria, and is also an essential element for the health of astronauts. An interesting fact is that on Earth, iodized water is considered too expensive for mass use, and chlorine is used instead of iodine. The use of chlorine on the ISS was abandoned due to the aggressiveness of this element, and the greater benefits of iodine.

Water consumption in space

To ensure the life of astronauts, a colossal amount of water is required. If a water regeneration system had not been established by now, space research would probably be stuck in the past. Taking into account water consumption in space, the following data is used per person per day:

2.2 liters - drinking and cooking;
0.2 liters - hygiene;
0.3 liters - toilet flush;

Water consumption for drinking and food practically corresponds to earthly standards. Hygiene and toilet - much less, although all this can be recycled and reused, but this requires energy costs, so costs have also been reduced. An interesting fact is that while a Russian cosmonaut receives 2.7 liters of water per day, American astronauts receive approximately 3.6 liters. The American mission continues to receive water from Earth, as do Russian cosmonauts. But unlike the Russian mission, the Americans receive water in small plastic bags, and our cosmonauts in 22 liter barrels.

Using Recycled Water

The average person might assume that astronauts on the ISS drink water recycled from their own urine and solid waste. In reality, this is not the case; for drinking and cooking, astronauts use clean spring water delivered from Earth. The water additionally passes through silver filters and is delivered to the ISS by the Russian Progress cargo spacecraft.

Drinking water is supplied in 22 liter barrels. Water obtained by processing urine and solid waste is used for technical needs. For example, water is necessary for the operation of catalysts and for the operation of the oxygen production system. Relatively speaking, astronauts “breathe urine” and do not drink it.

At the beginning of 2010, information appeared in the media that due to a breakdown in the water regeneration system on the ISS, American astronauts were running out of drinking water. Vladimir Solovyov, flight director of the Russian segment of the ISS, told reporters that the ISS crew never drank water obtained by regeneration from urine. Therefore, the breakdown of the American urine processing system, which actually existed at that time, did not affect the amount of drinking water. It is noteworthy that the American system failed twice for the same reason, and only the second time was it possible to establish the true cause of the problem. It turned out that due to the influence of space conditions, calcium in the urine of astronauts greatly increases. Filters for processing urine, developed on Earth, were not designed for such a biochemical composition of urine, and therefore quickly became unusable.

Production of oxygen from water

Soviet and then Russian scientists set the pace in the production of oxygen from water. And if in the issue of water regeneration, American colleagues have slightly surpassed Russian scientists, then in the issue of oxygen production, ours confidently hold the palm. Even today, 20-30% of recycled water from the American sector of the ISS goes to Russian oxygen production devices. Water regeneration in space is closely related to oxygen regeneration.

The first devices for producing oxygen from water were installed on the Salyut and Mir spacecraft. The production process is as simple as possible - special devices condense moisture from the air, and then produce oxygen from this water through electrolysis. Electrolysis - passing current through water - is a well-established scheme that reliably provides astronauts with oxygen.

Today, another source of water has been added to condensed moisture - processed urine and solid waste, which makes it possible to obtain process water. Process water from the American ECLSS apparatus is supplied to the Russian system and the American OGS (Oxygen Generation System), where it is then “processed” into oxygen.

Scientists are struggling to solve the problem - a 100% closed cycle to fully provide astronauts with water and oxygen. One of the most promising developments is the production of water from carbon dioxide. This gas is a product of human respiration, and currently this “product” of the life activity of astronauts is practically not used.

French chemist Paul Sabotier discovered an amazing effect, thanks to which water and methane can be obtained from the reaction of hydrogen and carbon dioxide. The current oxygen production process on the ISS involves the release of hydrogen, but it is simply thrown into outer space because there is no use for it. If scientists manage to establish an effective system for processing carbon dioxide, they will be able to achieve almost 100% closure of the system and find effective use of hydrogen.

The Bosch reaction is no less promising in the production of water and oxygen, but this reaction requires extremely high temperatures, so many experts see more prospects for the Sabotier process.

Publications by employees of JSC NIIkhimmash

Regeneration of water and atmosphere on a space station: experience of the Salyut, Mir and ISS orbital stations, development prospects

L.S. Bobe, L.I. Gavrilov, A.A. Kochetkov, E.A. Kurmazenko (JSC "NIIkhimmash"), P.O. Andreychuk, A.A. Zelenchuk, S.Yu. Romanov (NPO " Energy"), Yu.E.Sinyak (IMBP RAS). Report at the conference IAC-10.A1.6.6., 10.27.2010

Essay

Based on an analysis of the operating experience of the Russian space stations "Salyut", "Mir" and the International Space Station ISS, data on the balance of water and oxygen at the station, operating parameters and characteristics of water and atmospheric regeneration systems are presented. Based on these data, a design analysis of a complex of regeneration life support systems for a space station in lunar orbit was carried out. The proposed complex of physical and chemical life support systems includes: a comprehensive system for regenerating water from atmospheric moisture condensate, from the condensate of a vitamin greenhouse and water from a carbon dioxide recovery system; water regeneration system from urine; sanitary water regeneration system; oxygen regeneration system based on water electrolysis; system for purifying the atmosphere from microimpurities; a system for purifying the atmosphere from carbon dioxide and its concentration and a system for processing carbon dioxide; system of water, oxygen and nitrogen reserves. The launch mass of life support systems (including spare parts, backup equipment, equivalent mass of electricity consumption and heat discard) is acceptable for a lunar orbital station. A mandatory stage for testing new processes and systems for water and atmosphere regeneration for promising missions is their testing on the ISS.

Introduction

The implementation of promising orbital and interplanetary flights is associated with the improvement of crew life support systems (LSS). These systems must carry out maximum extraction and regeneration of water from water-containing products of human activity and the biotechnical complex, produce oxygen from regenerated water by electrolysis, purify the atmosphere from carbon dioxide and other impurities, convert carbon dioxide to produce water; meet the crew's needs for water and oxygen with minimal addition of these substances from reserves.

The sources of water and oxygen on board the station are human waste products: sweat and exhaled moisture collected in the air conditioning system (atmospheric moisture condensate); urine; carbon dioxide; moisture evaporated by plants; sanitary water, as well as water released by technical systems, for example, fuel cells of an electrochemical generator.

Due to energy, volume, and mass limitations on the space station, water and atmospheric regeneration systems will currently and in the near future rely on physicochemical processes. The use of biological processes and the reproduction of food are tasks of the future and will most likely be realized on planetary bases.

The experience of operating the life support systems of the Russian orbital space stations (OSS) "Salyut" and "Mir" and the international space station ISS, based on the regeneration of water and atmosphere with partial use of water and oxygen from delivered reserves, made it possible to obtain data on the balance of water and oxygen in space station and operating parameters of regeneration systems. The use of these data makes it possible to carry out a design analysis of life support systems for promising interplanetary and space stations.

The presented report examines systems based on physical and chemical processes. It is assumed that the vitamin greenhouse will also be included in the LSS complex. The degree of return (regeneration) of substances is considered on the basis of the balance of water used for consumption, production of electrolysis oxygen and other needs.

Experience in the development and operation of water and atmospheric regeneration systems. Ground tests as part of a complex of life support systems.

In 1967-1968 At IBMP, a complex of physical and chemical regeneration life support systems RSZhO NLC, equipped with systems developed and manufactured by NIIkhimmash, was tested. . The structural diagram of the NLC RSZhO complex is presented in Fig. 1 (option A). Physico-chemical regeneration systems ensured the vital activity of a crew of three people located in a sealed mock-up of an interplanetary spacecraft for a year. The complex included water regeneration systems from condensate of atmospheric moisture, urine and sanitary water; system for electrolysis production of oxygen from regenerated water; system for purifying the atmosphere from microimpurities; systems for purifying the atmosphere from carbon dioxide and concentrating it; a system for recycling carbon dioxide by decomposing it into water and methane using the Sabatier method. The fundamental possibility of long-term regenerative life support for a person in a confined space was experimentally confirmed.

Based on these studies and further work on the creation and operation of flight systems, the main methods of water and atmosphere regeneration were formed. The following methods are currently being implemented. To regenerate water from atmospheric moisture condensate, a sorption-catalytic method is used, followed by mineralization, silver preservation and pasteurization of purified water. The extraction of water from urine is carried out by distillation with sorption-catalytic purification of the distillate.

Regeneration of sanitary water is carried out by filtration followed by sorption purification. Oxygen is produced by electrolysis of an aqueous alkali solution using water regenerated from urine. Purification of the atmosphere from microimpurities is carried out by the sorption-catalytic method using regenerated sorbents. Purification from carbon dioxide by sorption on regenerated sorbents with its concentration during regeneration of sorbents. Processing of carbon dioxide by hydrogenation with hydrogen using the Sabatier reaction to produce water and methane. To implement these methods, small-sized equipment has been developed that can operate under space flight conditions. Of particular note is the equipment for carrying out the processes of hydrodynamics and heat and mass transfer in gas-liquid media under conditions of weightlessness.

Fig.1. Block diagram of the complex of regeneration life support systems of the space station.

A. Ground complex RSZHO NLC: all systems shown in the figure.
B. Complex RSZHO OKS "Mir": positions 1, 2, 3, 4, 5, 6, 9, 10, 11, 14, 15, 16, 17.
C. ISS RSZhO complex: positions 1, 2, 4, 5, 9, 10, 11, 14, 15, 16, 17.
D. RSZhO complex of a promising station: all systems shown in the figure.

Regeneration of water from atmospheric moisture condensate at Salyut stations

For use in flight, the SRV-K systems for regenerating water from atmospheric moisture condensate were initially developed for long-term orbital stations "Salyut". In January 1975, for the first time in the world practice of manned flights, the crew of the Salyut-4 space station consisting of A.A. Gubarev and G.M. Grechko used water reclaimed from condensate for drinking and preparing food and drinks. The system operated during the entire manned flight of the station. Similar systems of the SRV-K type operated at the Salyut-6 (1977-1981 - 570 days) and Salyut-7 (1982-1986 - 743 days) stations. The SRV-K system, together with the reserve system, provided the station with water and, along with the regeneration function, carried out purification of water with expired supplies, heating of reserve water and obtaining hot water for sanitary and hygienic procedures.

Life support for the crews of the Mir space station

On the orbital space station OKS Mir, for the first time in world practice, an almost complete (except for the system of concentration and utilization of carbon dioxide) complex of physical and chemical systems for regeneration of water and atmosphere was implemented, which largely ensured the long-term and efficient operation of the station in manned mode. The structural diagram of life support is presented in Figure 1 (option B). Regeneration of water from condensate of atmospheric moisture, urine and sanitary water was carried out in separate systems, and oxygen for breathing was obtained by electrolysis of water regenerated from urine. The purification of the atmosphere from microimpurities was carried out in the SOA-MP system; purification of the atmosphere from carbon dioxide was carried out in the "Air" system. Water supplies were delivered to the station by Progress cargo ships in Rodnik system tanks and EDV tanks. After the start of Russian-American cooperation, water generated in the fuel cells of the Space Shuttle was transferred to the Mir station for drinking and producing electrolytic oxygen. Regeneration systems ensured the receipt of high-quality water and oxygen and the purity of the atmosphere throughout the entire flight of the station. Some characteristics of the systems are presented in Table 1. The SRV-K system operated in the base module throughout the entire period of the manned flight from 03/16/86 to 08/27/99; the SPK-U, SRV-U and SOA MP systems operated in the Kvant 2 module from 01/16/90 to 08/27/99; the "Electron-V" system operated alternately in the "Kvant 1" and "Kvant 2" modules throughout the entire flight period, the "Air" system operated in the "Kvant 1" module from April 1987 until the end of the flight, the SRV-SG system operated briefly only for confirmation of functionality.

As you can see, the mass consumption during the regeneration of water and atmosphere is significantly lower than the mass consumption during its delivery to the space station. The specific mass consumption for the regeneration of water from atmospheric moisture condensate and for the production of oxygen amounted to 0.14 kg of system mass per 1 kg of water or oxygen produced. The specific mass consumption when cleaning the atmosphere from carbon dioxide was 0.08 kg of system mass per 1 kg of removed CO 2.

Mass consumption when delivering 1 kg of water is, taking into account the weight of the container, 1.25 kg/l H 2 O; when delivering oxygen - 2.8 kg/kg O 2 and 2.1 kg/kg CO 2 when delivering consumables to clean the atmosphere from CO 2 with non-regenerable absorbers. During the operation of the Mir station, due to the operation of regeneration systems, a mass saving of 58,650 kg of delivered cargo was achieved. It should also be noted that the energy consumption is uniquely low, especially in water regeneration systems of the SRV-K and SRV-SG types: 2 Wh/l of water and 8 Wh/l of water, respectively.

Life support for the crews of the International Space Station ISS

A similar life support complex (Fig. 1, option C), including systems for the concentration and utilization of carbon dioxide and a vitamin greenhouse and water regeneration from these systems, was supposed to be implemented in stages on the International Space Station ISS. Currently, the SM service module includes improved systems for water regeneration from atmospheric moisture condensate SRV-K2M, urine reception and conservation SPK-UM (1st part of the water regeneration system from urine), electrolysis oxygen production "Electron-VM", purification from microimpurities SOA-MP and purification from carbon dioxide "Air".

The characteristics of the improved systems are significantly better than those of the systems that operated on the Mir station. System performance has been significantly increased and mass and energy costs have been reduced. The productivity of the "Electron-VM" system is increased by 2 times compared to the "Electron-V" system and amounts to 160 nl O 2 per hour (to provide 6 people). The purification system from microimpurities, which initially included a regenerable adsorber ZPL, a non-regenerable adsorber FOA and a low-temperature catalytic filter PKF, was introduced on October 24, 2003 with a high-temperature catalytic filter PKF-T, which provides periodic high-temperature catalytic purification of the atmosphere from methane. In the SRV-K2M and "Electron-VM" systems, the specific mass consumption for obtaining (absorption) of the target product decreased by 1.5 - 2 times to 0.08 kg/kg and 0.07 kg/kg, respectively. Main characteristics of the operation of water regeneration systems on the International Space Station ISS since November 2, 2000. (start of manned flight) to 1.06.10. are given in Table 2. In the SRV-K2M system, 12,970 liters of atmospheric moisture condensate were regenerated to drinking conditions, which is 63% of drinking water consumption and 44% of the total water consumption at the station. In the "Electron-VM" and "Air" systems, 5835 kg of oxygen was obtained and 10,250 kg of carbon dioxide was absorbed. The operation of the systems made it possible to save more than 50,000 kg of water and equipment delivery weight, i.e. several launches of Progress cargo ships.

Notes * - decoding in the list of symbols and abbreviations; **taking into account water heating; ***- consumption of water reserves - 16660 l, total water consumption at the station - 29630 l, **** - for 6 people.

The operating efficiency of a life-support system can be significantly increased by increasing the degree of its isolation. During the period under review, 15,300 liters of urine with flush water were collected and removed on the Russian segment of the ISS. With a water recovery coefficient of 0.9, the amount of water regenerated in the SRV-UM would be 13,770 liters with the system’s own weight being 15% of the mass of the water obtained. The ISS also collected and removed 10,250 kg of carbon dioxide. In a carbon dioxide processing system using the Sabatier reaction, it would be possible to obtain about 4610 liters of water using hydrogen from the Electron-VM system. Receiving an additional 18,380 liters of water on board practically ensures the station's balance of water and oxygen. Thus, one of the priority areas for the development of the Russian segment of the ISS and promising stations is the introduction of systems for regenerating water from urine and systems for concentrating and processing carbon dioxide into the LSS. This will reduce the weight of water deliveries, increase the reliability of water supply and the station’s flight autonomy, while expanding the capabilities of delivering scientific equipment.

Water and atmosphere quality

Currently, extensive experience has been accumulated in assessing the quality of reclaimed water and stock water. At the end of each expedition, during visiting expeditions and during joint flights with the Shuttle spacecraft, samples of atmospheric moisture condensate, reclaimed water and water from the reserve system were taken and delivered to Earth. Table 3 shows generalized data for the entire period of the ISS flight under consideration. As can be seen, despite the relatively high content of organic impurities in the condensate, the reclaimed water fully meets the standards. Drinking water from reserves retains its composition and meets all regulatory requirements. Bacteriological analyzes periodically carried out by American astronauts directly on board the station showed that there is practically no microflora in the regenerated water and in the water of reserves. The data presented convincingly confirm the chemical and bacteriological safety of water on the space station. The content of impurities in the station's atmosphere does not exceed the standards. The content of main impurities in electrolysis oxygen is given in Table 4. As you can see, the quality of oxygen fully satisfies the requirements.

Prospects for the development of a complex of regenerative life support systems

Based on the experience in the development and operation of water and atmospheric regeneration systems, the report examines a promising physicochemical system for the regenerative life support of an interplanetary station. Let us consider, as an example, the regenerative life support of a space station in lunar orbit with a crew of up to 4 people. Delivery of cargo to such a station is extremely difficult, so the optimal solution for this purpose is a complex of regenerative liquid-liquid systems that is practically closed in water and oxygen. The complex is presented in Fig. 1 (option D) and includes all the physical and chemical regeneration systems shown in the diagram, sanitary and hygienic equipment and a vitamin greenhouse with an illuminated area of 0.4 m². Food supplies containing 0.6 kg per person per day of dry matter and 0.5 kg per person per day of water are used. The technical balance for water is given in Table 5. The first column on the right and left sides of the table refers to the structure of the ISS life support system with minimal water requirements. Column 2 takes into account the water requirements for the vitamin greenhouse and water for washing and washing. Column 1.2 characterizes the first stage of development of LSS with the introduction of a system for regenerating water from urine and systems for concentrating and processing CO 2 (according to the Sabatier method). Column 2 characterizes the second stage of development of LSS with the introduction of sanitary and hygienic equipment, a vitamin greenhouse and appropriate water regeneration systems. An estimated calculation of the mass and energy consumption of the LSS complex for this option is presented in Table 6. Based on an analysis of the possibilities of increasing the service life of units and equipment of regeneration systems, the specific mass costs per 1 kg of the resulting product were reduced to the values given in the table. The load on the systems is based on the balance of substances given in Table 5.

Consumption, release and return capabilities of substances on the space station (for 1 cosmonaut per day)

The losses of water and atmosphere and the consumption of nitrogen for purging the capsule of the Electron-VM system, the exact values of which are unknown, were not taken into account. The consumption of water and atmosphere for spacesuits is also not taken into account. The specific gravity of the delivered water reserves is assumed to be 1.3 kg/kg H 2 O, oxygen - 3 kg/kg O 2. Emergency supplies were taken for 90 days based on the needs for oxygen and nitrogen (5 kg/person-day) and water (4 kg/person-day). American data on mass consumption for energy supply and heat removal in the thermal management system were used: 230 kg/kW and 146 kg/kW, respectively. It was assumed that the amount of heat removed is equivalent to the cost of electrical energy, the total accounting is 0.4 kg/W. When calculating the energy consumption of the SRV-K and SRV-SG systems, the costs of heating water were taken into account. It should be emphasized once again that, in accordance with the focus of the report, the costs of mass and energy for the regeneration of water and the atmosphere were considered. The remaining cost items for life support are: air conditioning, food, sanitary and hygienic and medical equipment, systems for extravehicular activities, etc. were not considered.

The estimated costs of mass and energy for the stay of 4 people in lunar orbit for a year were:
- for water regeneration and water supply of 2810 kg of equipment and water supplies and 280 W of electrical energy (daily average);
- for regeneration and atmospheric reserves 2630 kg of equipment and oxygen and nitrogen reserves and 1740 W of electrical energy (daily average).
The total costs for water and atmosphere regeneration and supplies amounted to 5440 kg (equipment and supplies of water, oxygen and nitrogen) and 2020 W of electrical energy (daily average).

The mass of emergency reserves is comparable to the costs of regeneration, so it is necessary to provide technical prerequisites for its reduction. Particular attention should be paid to the regeneration coefficients of substances and to minimizing losses of water and atmosphere, which directly affect the consumption of reserves (these losses were not taken into account in the calculations). The main direction of development of life-support systems is to increase their isolation and reliability. To increase reliability, the life support system must include not only spare units, but also backup systems that provide the crew with water and atmosphere in the event of a malfunction of the main systems. With increasing flight duration and autonomy, increasing the service life of equipment, ensuring maintainability, reducing the weight and energy consumption of systems and reducing the volume they occupy become crucial. It is necessary to improve the efficiency of existing and develop new processes for water and atmosphere regeneration.

*Taking into account additional units and backup subsystem. **Including emergency stock.

At present, there are no life support systems and complexes that fully meet these requirements. To create them, it is necessary to carry out targeted research and development work. The most important stage of testing new technological processes and systems for long-term autonomous flights is their testing and development on the international space station ISS.

When organizing planetary bases, it is necessary to ensure a gradual transition from the equipment of interplanetary ships operating in zero gravity to simpler equipment that uses the gravity of planets. A separate task is the development of processes and systems that use planetary resources.

conclusions

1. Regeneration life support systems have been created that have successfully operated on the Russian space stations "Salyut", "Mir" and currently on the ISS, ensuring a long stay of cosmonauts at the station and a significant technical and economic effect.

2. The analysis carried out, using the achieved experience, confirms the technical feasibility of creating a complex of life support systems based on the regeneration of water and atmosphere for the lunar orbital space station.

3. To solve this problem, it is necessary to increase the degree of closure of the LSS complex by increasing the coefficients of water extraction and introducing into the LSS systems systems for regenerating water from urine, concentrating and processing carbon dioxide.

At the second stage of improving the LSS complex, it is necessary to increase its comfort and introduce sanitary and hygienic equipment, a vitamin greenhouse and appropriate water regeneration systems.

4. The creation of complex life support systems for advanced missions requires the development of improved equipment, systems and technologies that make it possible to increase the reliability of regeneration and significantly reduce the mass consumption to obtain target products. It is also necessary to develop and implement backup systems that provide functional duplication of the main systems in emergency situations.